JP2003181532A - Method for continuously manufacturing metal tube welded in longitudinal direction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal tube which can reduce not only an outer diameter but also a thickness of a wall without a problem in the step to be conducted later after the long metal tube is manufactured. <P>SOLUTION: The method for continuously manufacturing the metal tube welded in a longitudinal direction comprises steps of drawing a metal strip from a strip stock, gradually molding the longitudinal strip to a tube not yet closed, and closing the longitudinal strip by brazing or welding. The method further comprises a step of introducing a lubricant to the slit tube not yet closed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

The invention relates to a method according to the preamble of claim 1.

[0002]

BACKGROUND OF THE INVENTION Methods for continuously producing longitudinally welded metal tubes, whether smooth or corrugated, have been known for some time.

[0003] From "special pamphlet" (Uniform Document 1) concerning Uniwema machines and accessories of kabelmetal electro limited company, it is possible to use metal pipes having a diameter of 2 to 400 mm and a wall thickness of 0.05 to 4.0 mm. Methods are known that can be manufactured with infinite length.

In this case, the metal strip wound on the reel is drawn out, optionally cleaned, and slit (unsewn) tubing (Schl) in several forming steps of the forming table.
and the longitudinal slit of the slit tube is welded with a welding device. This metal pipe is a so-called collet chuck pulling device (Sp
The pulling device conveys the metal strip and the metal tube at a uniform speed. For this purpose, a collet chuck mounted on two endless roller chains grips this tube. The collet chuck is equipped with a gripper that is precisely adapted to the tube diameter.

The welded tube is usually then wound onto a cable reel.

In this known method, the metal strip is formed into a slit tube and the longitudinal edges are welded, so that a tube with an outer diameter of 2 mm or less cannot be produced. In order to be able to manufacture tubes of diameter less than this, the tubes must be drawn in one or more steps. The tube is then withdrawn through a die, the inner diameter of this die being smaller than the outer diameter of the tube to be withdrawn. If it is desired to also reduce the wall thickness of the tube during the drawing operation, a mandrel (Dorn) must be introduced into the tube and the outer diameter of the mandrel must be larger than the inner diameter of the die.

A lubricant must be provided to reduce the friction between the tube wall and each forming tool (die and mandrel). Lubrication of the outside of the pipe is almost no problem. However, when the pipe to be drawn is long, it is difficult to put the required amount of lubricant inside the pipe.

[0008]

[Non-Patent Document 1] kabelmetal electr
o Uniwema Machines and Accessories of Uni Limited (Uniwema-Maschoen und Zu
be der Fiema kabelmeta
l electro GmbH) “Specialized brochure (Fachprospect)”

[Patent Document 1] West German Patent Application Publication No. 1164355

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to provide a method by which long metal tubes can be produced and, in subsequent steps, not only the outer diameter but also the wall thickness can be reduced without problems.

[0010]

This problem is solved by the features of claim 1.

Advantageous embodiments of the invention are mentioned in the dependent claims.

An essential advantage of the present invention is that a precisely dosed coating of lubricant on the inner surface is possible in a simple manner. This allows the subsequent drawing process to be carried out without problems, ie without damaging the inner surface of the tube and thus without risk of breaking the tube behind the die.

The present invention will be described in more detail by showing an embodiment in a schematic diagram.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION From a stock reel 1, a metal strip 2 made of austenitic steel, for example, is drawn out and supplied to a forming roller set 3, where the metal strip 2 is placed.
Are gradually molded into a tube 4 having a longitudinal slit.
This longitudinal slit is closed by a welding device 5, preferably a laser welding device. The welded pipe 6 is captured behind the welding device 5 by a collet chuck withdrawing device 7, which brings the metal strip 2, the slit pipe 4 and the welded pipe 6 together in this manufacturing facility. And pull it. This collet chuck pulling device is disclosed in German Patent Publication No. 1164.
No. 355 (Patent Document 1).

The welded pipe 6 is subsequently wound on a cable drum 8.

The above method is limited to tubes with an outer diameter of up to 2 mm.

There is a demand for a metal tube having an outer diameter of 0.2 mm and a wall thickness of 0.02 mm. Such a metal tube is used for manufacturing an injection needle.

In order to be able to manufacture a metal tube of such dimensions, the longitudinally welded tube produced by the above method must be pulled out in multiple steps to reduce it to the desired dimensions. I have to.

In order to make the longitudinally welded pipe suitable for the subsequent drawing operation, the present invention provides a thin lubricant film on the inner surface of the metal pipe 6.

For this purpose, a lance 9 is used to connect the storage container 10 to the slit tube 4 or the metal tube 6.
Introduce a lubricant.

In order to prevent the lubricating properties of the lubricant from being impaired by the heat of welding, it is particularly advantageous to position the end of the lance 9 behind the welding device.

The introduction of the lubricant into the slit tube 4 or the welded tube 6 by the lance 9 can be discontinuous. When subsequently wound on the cable drum 8 or reel, the lubricant is distributed over the entire inner surface of the tube 6.

As an alternative to the above, a thin film can be applied to the inner surface of the tube 6 behind the welding device 5 by spraying with a lubricant. According to the method of the present invention, a pipe having a long pipe length, that is, a pipe welded in the longitudinal direction of 20,000 m or more can be manufactured, and a drawing process to be performed thereafter makes
From this tube it is possible to produce tubes with very small outer diameter and wall thickness.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment according to the present invention.

[Explanation of symbols]

1 stock reel 2 metal strip 3 forming roller set 4 slit tubes 5 Welding equipment 6 tubes 7 Collet chuck pulling device 8 cable drum 9 Lance 10 storage containers

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) B23K 26/00 B23K 26/00 310W // B23K 101: 06 101: 06 103: 04 103: 04 F term (reference) 4E028 CA02 CA13 CA18 CA20 4E068 AA02 BG01 DA15 DB01 4E096 EA16 JA11

Claims (7)

[Claims] 1. A method for continuously producing a longitudinally welded metal tube, wherein a metal strip is drawn from a stock of strips and gradually formed into an unclosed tube having a longitudinal slit, the longitudinal direction being A method, characterized in that the slits are closed by brazing or welding and the lubricant is introduced into the slit tubes which are not yet closed. 2. Method according to claim 1, characterized in that a lubricating oil is introduced. 3. Method according to claim 1, characterized in that the lubricant is introduced as drops. 4. Method according to claim 1, characterized in that a lubricant is introduced into the metal tube behind the welding point by means of a lance. 5. The method according to claim 1, wherein the longitudinal slit is closed by laser welding. 6. Introducing a lubricant into the slit tube which is not yet closed, the amount of the lubricant being such that after winding the tube the entire inner surface of the metal tube is wetted with the lubricant. 6. A method according to any one of the preceding claims, characterized in that the welded tubes are wound into a coiled bundle or wound onto a reel. 7. In a post-working step, not only the outer diameter of the metal tube but also the wall thickness is reduced by a drawing process using a mandrel inside the tube and a drawing die, characterized in that 6. The method according to any one of 6.